This disclosure generally relates to functionalized silicone resin compositions and their use for the production of bisphenols. The disclosure further relates to methods for preparing these functionalized silicone resin compositions.
Bisphenols are valuable raw materials for producing polycarbonates. Polycarbonates are widely used in a variety of applications by virtue of their excellent physical properties, such as impact resistance, mechanical characteristics, transparency, and the like. Bisphenols are generally obtained by the reaction of a carbonyl compound with a phenol in the presence of an acidic catalyst, such as mineral acids or acidic ion exchange resins. One example of such acidic ion exchange resins is sulfonated polystyrene resin cross-linked with divinylbenzene, (PS-DVB). Frequently, a co-catalyst is used in conjunction with the acidic catalyst, to improve the selectivity for bisphenol such as the para, para-bisphenol isomer, for example. Co-catalysts can be present as unattached molecules in the bulk reaction matrix, e.g., “bulk co-catalysts”, or can be attached to the acidic resin catalyst through ionic or covalent linkages. Mercaptans are one class of co-catalysts that can be employed. More specifically, thiols, e.g., organosulfur compounds derived from hydrogen sulfide, are used as co-catalysts. Numerous efforts have been made to improve the selectivity for bisphenols by varying the mercaptan co-catalyst and the acidic catalyst. One approach that has been attempted is to use a catalyst having an attached co-catalyst, which is prepared, for example, by reacting a portion of the acidic groups of the acidic ion exchange resins with aminomercaptans, to provide catalysts containing both mercaptan and sulfonic acid groups.
When ion exchange resin catalysts are used for making bisphenols by reaction of phenols with carbonyl compounds, the lifetime of the catalyst is affected by numerous factors, such as, for example, mechanical strength and fouling tendency. In addition, ion exchange resin catalysts typically include a pre-conditioning step, especially in continuous processes. Pre-conditioning is generally performed by passing the phenol through a packed bed of the ion exchange resin catalyst.
In view of these problems, there remains a need for alternative catalysts that have built-in functionalities for performing as a catalyst and a co-catalyst, and also allow for improved bisphenol selectivity, particularly for the para, para-bisphenol isomer. Furthermore, the alternative catalysts desirably have potentially superior mechanical properties as compared to the traditionally used ion-exchange resin catalysts, thereby leading to improved catalyst lifetime and bisphenol productivity.